Process of obtaining oxid and carbonate of zinc from materials containing zinc.



UNITED STATES PATENT OFFICE.

GILBERT RIGG, OF SWANSEA, ENGLAND.

PROCESS OF OBTAINING OXID AND CARBONATE F ZINC FROM MATERIALS CONTAININGZINC.

SPECIFICATION forming part of Letters Patent No. 654,804, dated July 31,1900. Application filed May 6, 1899. Serial No. 715,855. (No specimens.)

To all whom it may concern.- 7

Be it known that I, GILBERT RIGG, a subject of the Queen of GreatBritain and Ireland, residing atBryn road, Swansea, in the county ofGlamorgan, Wales, England, have invent ed a Process for the Productionor Separation of Oxid of Zinc and Carbonate of Zinc from Ores and otherMaterials Containing Zinc, of which the following is a specification.

16 The object of my invention is to produce or separate oxid of zinc andcarbonate of zincfrom ores and other materials containing zinc.

I have discovered that when material containing zinc in either themetallic form or as oxid or carbonate, or in two or all of these forms,is leached with a solution of carbonate of ammonia or of carbonate ofammonia and ammonium hydrate there is for any given percentage ofammonia in the solution a cerzo tain percentage of carbon dioxid atwhich the capacity for dissolving zinc possessed by the solution is at amaximum. Any alteration in the amount of carbon diofxid in the solutionalso causes alteration in its capacity for dissolving zinc if thequantity of ammonia remains constant. If the quantity of carbon dioxidin the solution be increased, the dissolving capacity of the solution isaugmented up to a certain point, beyond which any fur- 3o ther increasecauses the dissolving capacity to again decrease. I

The mode of practicing my invention isas follows: When in the materialto be treated the zinc to be dissolved according to this invention isnot in either the metallic. form or that of an oxid or a carbonate, thematerial is subjected to a preliminary treatment in order to convert thezinc into one or some of said forms. For example, if dealing with sulfidof zinc the same is converted into oxid of zinc by calcination, as wellunderstood. The material or mixture of materials containing metalliczinc or oxid of zinc or carbonate of zinc, or two or all of these, isleached with a solution of ammonium carbonate or ammonium carbonate andammonium hydrate in order to dissolve any contained metallic zinc, oxidof zinc, and carbonate of zinc, or either, and in order to separate theoxid of zinc and 5a carbonate of zinc, or either, the proportion ofcarbon dioxid in the solution is changed by additions or subtraction, orthe action of the carbon dioxid so present is partially counteracted byintroduction of suitable material for which it has an aifinity andwhereby part of the carbon dioxid is absorbed. By this separatingprocess I can separate oxid of zinc and carbonate of zinc from asolution obtained otherwise than by leaching ores or other materialscontaining zinc, provided such solution be of the same nature as abovedescribed. Having decided on what amount of ammonia -is to be used inthe solution, it is obviously advantageous to use for leaching purposesthat amount of carbon dioxid which will impart the greatest possibledissolving capacity to the" solution. As will be evident, this caneasily be settled once for all by tests. 'In the case of two solutionswhich Ihave used containing, respectively, 1.2 and 1.4 I

pounds ammonia (N11 per gallon I find that the following are thedissolving capacities (expressed in pounds of zinc oxid per gallon)corresponding to the various amounts of carbon dioxid given in thetable:

Solution No. 1.NH 1.2 pounds per gallon.

If using solution No. 1, I 'should' employ 1.1 pounds carbon dioXid (COfor leaching pur- 10o poses; if solution No. 2, 1.3 pounds. Then I caneither increase the amount of carbon dioxid in the solution by blowingin additional gas or diminish the amount by adding material.-forexample, lime or caustic soda-w'ith which some of the carbon dioxid.

vantage that it is difficult to reduce the quantity of carbon dioxidpresent withoutadding something which will adulterate the product or thesolution. I therefore prefer the former-that is, the precipitationbyaddition of carbon dioxid. 1 The extent to which the precipitation isto be carried is determined I 5 by various considerations. It the carbondioxid is added to an extent which will cause some of the ammonia to beconverted into bicarbonate, there is a tendency for this bodytocrystallize out, especially when the amount of ammonia present israther large-say asin solution No. 2. This bicarbonate can, however,always be recovered by washing the precipitate. In the case of afourteen-percent-ammonia solution (1.4 pounds NH per gallon) I mightstart with about 1.3 pounds carbon dioxid per gallon for leaching andincrease to about 1.7 duringprecipitation. This would. allow a fairyield of precipitate without any serious amount of crystallization. Thesolution is rendered fit for leaching again by removing the excess of.carbon dioxid by lime or other suitable means. Although I have statedcertain suitable proportions by way of example, it is to be noted thatthey aresubject to variation, as

may prove desirable in actual working. If it is desired to obtain a pureand white product and the solution has acquired any contaminationthrough iron or copper con- 0 tained in thezi-nc-containing material,the

iron must be removed from solution by mixing hydrated oxid of tin(metastannic acid) with the solution and allowing the precipitate tosubside or by other suitable means, and the copper must be removed byplacing metallic zinc in the solution on which the copper deposits.

The term oxygen compound of zinc herein used is only intended tocomprise ox- 5o ids and carbonates of that metal.

What Ic-laim is-- I 1. The processof producing oxid of zinc andcarbonate of zinc. from zinkiferous material which consis ts in leachingthezinkiferous ma 5 5 terial with asolution of ammonia and carbon dioxidwherein the carbon dioxid is in such proportion to the ammonia as toimpart to the latter an approximately maximum zinc-dissolving capacity,as herein set forth. 6o 2. The process of producing oxid of zinc andcarbonate of zinc'from material containing an oxygen compound of zincwhich consists in leaching the zinkiferous material with a solution ofammonia and carbon dioxid wherein the carbon dioxid is in suchproportion to the ammonia as to impart to the latter an approximately-maximum zinc-dissolvin g capacity, as herein set forth.

- 3. The process of producing oxid of zinc and carbonate of zinc frommaterial containing carbonate of zinc which consists in leaching the,zinkiferous material with a solution of ammonia and carbon dioxidwherein the carbon dioxid is in such proportion to the ammonia as toimpart to the latter an approximately-maximum zinc-dissolving capacity,as herein set forth. 7

4=- Theprocess of producing oxid of zinc and carbonate of zinc fromoxidof zinc and carbonate of zinc which consists in leaching the zinciferousmaterial with a solution of ammaximum zinc-dissolving capacity, asherein set forth. 7

5. The process of producing oxid of zinc and carbonate of zinc fromzinkiferous material material with a solution of ammonia and carbondioxid wherein the carbon dioxid is in such proportion to the ammonia astoimpart .to the latter an approximately-maximum zincdissolvingcapacity, as herein set forth and oxid. of zinc and carbonate of zinccontained therein by altering the amount of the active carbon dioxidcontained in said solution.

6. The process herein described for producing or separating oxid andcarbonate of zinc from material containing an oxygen compound of zincwhich consists in leaching the zinkiferous material with a solution ofammonia and carbon dioxid wherein the carbon dioxid is in suchproportion to the ammonia as to impart to the latter'an approximatelysetforth and subsequently separating from the solution oxid of zinc andcarbonate of zinc contained therein by altering the amount of the activecarbon dioxid contained in said solution.

carbonate of zinc from zinkiferous ores or other materials whichconsists inleaching'the of the active carbon dioxid con-taine'd'in saidsolution while keeping constant the quantity of ammonia, substantiallyas described.

ing or separating oxid and carbonate of zinc from material containing anoxygen compound of zinc which consists in leaching the said materialwith a solutionof ammonia and carbon dioxid wherein the carbon dioxid ismonia and carbon dioxid wherein the carbon. dioxid is in such proportionto the ammonia as to impart to the latter an approximatelywhich consistsin leaching the zinkiferous' subsequently separating from the solution7. The process of producing oxid of zinc and the solution oxid of zincand carbonate of zinc contained therein by altering the amount maximumzinc-dissolving capacity, as herein .-.zinkiferous material with asolution of am- 8. The process hereindescribed for producin suchproportion to the ammonia as to impart to the latter anapproximately-maximum zinc-dissolving capacity, as herein set forth, andsubsequently separating from the solution oxid of zinc and carbonate ofzinc contained therein by altering the amount of the active carbondioxid contained in said solution while keeping constant the quantity ofammonia, substantially as described.

9. The process herein described for producing or separating oxid of zincand carbonate of zinc from zinkiferous ores or other material whichconsists in leaching the zinkiferous ore or material with a solution ofammonia and carbon dioXid wherein the carbon dioxid is in suchproportion to the ammonia as to impart to the latter anapproximately-maximum (lissolving capacity and subsequently separatin' ging a solution containing ammonium carbon-.

ate, oxid of zinc, and carbonate of zinc which consists in separatingthe oxid of zinc and carbonate of zinc from the solution by altering theproportion of active carbon dioxid in the said solution as set forth.

11. The herein-described process for separating oxid of zinc andcarbonate of zinc from zinkiferous material which consists in leachingthe said material with a solution of ammonium carbonate and ammoniumhydrate containing carbon dioxid in such proportion to the ammonia inthe solution as to impart to the solution a maximum zinc-dissolvingcapacity, as herein set forth, and subsequently separating from thesolution oxid of zinc and carbonate of zinc by increasing the proportionof carbon dioxid in the solution while keeping constant the quantity ofammonia, substantially as described.

12. The process herein described of treating a solution containingammonium carbonate, oxid of zinc and carbonate of zinc by increasing theproportion of carbon dioxid to the ammonia in the said solution as setforth.

Signed at the county borough of Swansea, Wales, this 24th day of April,1899.

GILBERT RIGG.

Witnesses:

ERNEST BENNETT CLEGG, WALTER HERBERT ORIcHToN.

